Apparatus and method for minimizing the turn on time for a receiver operating in a discontinuous receive mode

Abstract

An apparatus and a method for minimizing the turn on time for a receiver operating in a discontinuous receive mode. In a communication unit the receiver receives a signal (118) having desirable data (word A) and undesirable data (word B). The receiver (104) has a discontinuous receive mode of operation wherein the receiver (104) is turned on when expecting the desirable data (word A) and turned off when expecting the undesirable data (word B). A duration of time that the receiver (104) has been turned off is determined. The receiver (104) is turned on at time prior to the arrival of the desirable data (word A) responsive to the duration of time that the receiver (104) has been turned off. The present invention advantageously minimizes the turn on time for the receiver (104) operating in a discontinuous receive mode to save current drain.

What is claimed is: 
     
       1. In a communication unit including a receiver that receives a signal including at least a first word block and a second word block, wherein each word block has a predetermined time duration, wherein each word block has desirable data words repeated therein, and wherein the receiver has a discontinuous receive mode of operation wherein the receiver is selectively turned on and off, a method for minimizing a turn on time for the receiver operating in the discontinuous receive mode, the method comprising the steps of: turning on the receiver at a predetermined time prior to the arrival of each occurrence of the desirable data word;   verifying the integrity of the desirable data word responsive to receiving a number of occurrences of the desirable data word;   turning off the receiver for any remaining occurrences of the desirable data word within the predetermined time period responsive to the step of verifying the integrity of the desirable data word;   determining a variable time period that the receiver will be turned off responsive to the number of occurrences of the desirable data word used in the step of verifying and the predetermined time period; and   turning on the receiver at a time prior to the arrival of the second word block responsive to the variable time period.   
     
     
       2. A method according to claim 1 further comprising the steps of: determining an indication of at least one of phase and frequency of the signal when the receiver is turned off;   holding the indication of the at least one of the phase and the frequency of the signal responsive to the step of determining the indication; and   measuring the duration of time that the receiver has been turned off responsive to the held indication of the at least one of the phase and the frequency of the signal.   
     
     
       3. In a communication unit including a receiver that receives a signal including at least a first word block and a second word block, wherein each word block has a predetermined time duration, wherein each word block has desirable data words repeated therein, and wherein the receiver has a discontinuous receive mode of operation wherein the receiver is selectively turned on and off, an apparatus for minimizing a turn on time for the receiver operating in the discontinuous receive mode, the apparatus comprising: a controller for: turning on the receiver at a predetermined time prior to the arrival of each occurrence of the desirable data word;   verifying the integrity of the desirable data word responsive to receiving a number of occurrences of the desirable data word;   turning off the receiver for any remaining occurrences of the desirable data word within the predetermined time period responsive to the step of verifying the integrity of the desirable data word;   determining a variable time period that the receiver will be turned off responsive to the number of occurrences of the desirable data word used in the step of verifying and the predetermined time period; and   turning on the receiver at a time prior to the arrival of the second word block responsive to the variable time period.     
     
     
       4. An apparatus according to claim 3 further comprising: a demodulator, operatively coupled to receive the signal, for generating a data clock signal indicative of at least one of phase and frequency of the signal;   wherein the controller measures the duration of time that the receiver has been turned off responsive to the data clock signal.